With the campaign still up for grabs, the two sides in Minnesota's heated marriage amendment fight squared off Thursday night in their only debate.

The Rev. Jerry McAfee, a Baptist minister in Minneapolis who has worked to mobilize the black community in support of the amendment that would define marriage as between a man and a woman, said he worries that failure to pass the measure could soon lead to legalization of same-sex marriage in the state.

"If you add to the definition of marriage, you change my belief system," McAfee said.

Marriage amendment opponents said the amendment could have a chilling effect on the evolving conversation about same sex marriage.

"I would like future generations to be able to continue the conversation," said Sarah Walker, a board member for Minnesotans United for All Families, the lead group trying to defeat the measure.

The debate came in the final days of a marriage amendment fight that has been the most expensive and hard-fought ballot question in state history. A new Star Tribune Minnesota Poll show the contest is a dead heat, so both sides have enormous stakes in successfully making their closing arguments to voters. Minnesota airwaves are peppered with ads from both sides as the campaigns fire up their enormous get-out-the-vote machinery to remind supporters to vote Tuesday.

The amendment also has put Minnesota squarely at the forefront of a national debate about same-sex marriage. Three other states are dealing with marriage-related measures Tuesday: Maine, Maryland and Washington. Thursday's debate had a more national flavor, too, featuring Brian Brown of the National Organization for Marriage and the Rev. Gene Robinson, the Episcopal Church's first gay bishop.

The debate took many testy turns, with heated contention over the Bible and sometimes tense discussions about same-sex marriage and the civil rights movement.

State law already doesn't recognize same-sex marriage, but supporters argue that court cases and proposals in the Legislature could change that without a vote of the people.

"All the amendment does is take the current definition of marriage and make sure that judges and politicians don't change the definition," said Brown, whose organization is the single-largest contributor to pro-amendment forces in Minnesota.

The amendment does not quash the debate on marriage, it merely ensures that Minnesota voters have the ultimate say, Brown said. "I trust Minnesotans, not the courts,"

But Robinson said that sometimes the courts are the best way to ensure a minority group isn't discriminated against by the majority.

"Thank God for the courts," Robinson said at the debate hosted by Minnesota Public Radio at the Fitzgerald Theater in downtown St. Paul. "If we had depended on the popular vote to get rid of Jim Crow laws and discrimination, God only knows how long it would take to get there."

Robinson said passing the amendment sends a terrible message to people struggling with their true sexual identity.

"We have kids jumping off bridges ... due to the grim outlook of their life," he said. The last thing we want to do is be "telling them their lives will not count in Minnesota."

Both sides dove into an issue that has simmered throughout the months-long fight: whether the fight for same-sex equality and marriage is comparable to the civil rights movement.

McAfee insisted they aren't.

"No group, other than American Indians, has gone through the tragedy and the travesty that we have," he said.

In a rare moment of agreement, Robinson concurred.

"This is not the same," Robinson said during the hour-long debate. But he also urged groups who have experienced discrimination not to "fight with each other."

Brown rejected months of criticism that his side of the campaign is driven by bigotry and a desire to discriminate.

"It is not discrimination to say there is something unique about marriage," Brown said. "It is not motivated by hate to stand up for this beautiful thing."

Minnesota requires amendments to win 50 percent of all ballots cast to become law. So skipped ballots count as no votes, a twist that has supporters clawing for every vote in what could prove to be an election-night nail-biter.

In these frantic final days, both campaigns are strengthening their efforts to reach out to religious voters, a group that has been a powerful force in marriage amendment fights in other states.

Amendment supporters Pastors for Marriage announced at midday that more than 500 Christian pastors and leaders have endorsed the amendment and are urging congregants to vote yes on Election Day.

Those faith leaders represent Minnesota Assemblies of God, Lutheran, Baptist, Presbyterian, Catholic and other churches, according to a released statement from the group, which is a member of the coalition Minnesota for Marriage, the main group campaigning in support of the amendment.

"As the author and architect of marriage, God has spoken clearly that marriage is to be between a man and a woman," said the Rev. Steve Goold of New Hope Church.

Marriage amendment opponents are working just as hard to woo Minnesotans of faith.

More than 1,000 Minnesotans, including Minneapolis Mayor R.T. Rybak, joined about 150 clergy from a range of denominations opposed to the amendment for a service at Hennepin Avenue United Methodist Church in Minneapolis Thursday.

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